4GB Kit (2GB x 2) DDR PC3200 (400MHz) Memory Module CL=3 Registered ECC 2.6V 256Meg x 72 184-pin DIMM. A dual inline memory module (DIMM) consists of a number of memory components (usually black) that are attached to a printed circuit board (usually green). The gold pins on the bottom of the DIMM provide a connection between the module and a socket on a larger printed circuit board. The pins on the front and back of a DIMM are not connected to each other. 184-pin DIMMs are used to provide DDR SDRAM memory for desktop computers. To use DDR memory your system motherboard must have 184-pin DIMM slots and a DDR-enabled chipset. A DDR SDRAM DIMM will not fit into a standard SDRAM DIMM socket. (Information about which memory technology your system uses is included in the Crucial Memory Advisor tool.) The number of black components on a 184-pin DIMM can vary but it always has 92 pins on the front and 92 pins on the back for a total of 184. 184-pin DIMMs are approximately 5.25 inches long and 1.25 inches high though the heights can vary. While 184-pin DIMMs and 168-pin DIMMs are approximately the same size 184-pin DIMMs have only one notch within the row of pins.